Asymmetrical hail timing

Abstract

A method includes transmitting first hail messages from a first device at a first hailing rate, wherein a first time between beginnings of each consecutive first hail message is a first period, each first hail message transmitted for a first length of time, and a first gap extends between an end of each first hail message and a start of a next first hail message; listening at the first device for a second hail message repeatedly transmitted at a second hailing rate, wherein a second time between beginnings of each consecutive second hail message is a second period, each second hail message transmitted for a second length of time, and a second gap extends between an end of each second hail message and a start of a next second hail message; and performing, at the first device, a channel activity detection of a preamble in the second hail message.

That which is claimed is: 
     
       1. A method of communicating hail messages, comprising:
 repeatedly transmitting, by a first device to a second device, a hail message, each transmission of the hail message alternating between two channels; 
 wherein the hail message includes a preamble portion and a data portion separated from one another by a frame, the preamble portion comprising a sequence of symbols and defining a valid channel activity detection (CAD) window extending from a start of the hail message up to a predetermined number of symbols preceding the frame, the preamble portion further defining an invalid CAD window extending for the predetermined number of symbols preceding the frame; 
 encountering a failure, during at least one of a first transmission of the hail message and a second transmission of the hail message, to temporally align an instance of listening by the second device with the valid CAD window of the preamble portion; and 
 after encountering the failure, temporally aligning the valid CAD window of the preamble portion with another instance of listening by the second device, the temporal aligning of the valid CAD window with the another instance of listening by the second device avoiding the invalid CAD window of the preamble portion, and the temporal aligning occurring by no later than an event selected from one of a third transmission of the hail message, the third transmission occurring on one of the two channels, and a sixth transmission of the hail message, the sixth transmission occurring on another one of the two channels. 
 
     
     
       2. The method of  claim 1 ,
 wherein the hail message repeatedly transmitted by the first device is a first hail message, each transmission of the first hail message comprising a first hail repetition, 
 wherein the first device repeatedly transmits the first hail message at a first hailing rate, wherein a first time between beginnings of each first hail repetition is a first period, each first hail repetition is transmitted for a first length of time, and a first gap extends between an end of each first hail repetition and a start of an ensuing first hail repetition, and 
 further comprising listening at the first device for a second hail message being repeatedly transmitted to the first device at a second hailing rate, each transmission of the second hail message comprising a second hail repetition, wherein a second time between beginnings of each second hail repetition is a second period, each second hail repetition is transmitted for a second length of time, and a second gap extends between an end of each second hail repetition and a start of an ensuing second hail repetition, 
 wherein the first period is greater than the second period, the first length of time is greater than the second length of time, and the first gap is greater than the second gap, 
 wherein the first device listens for the second hail message at a first listening rate that is less than a second listening rate of the second device. 
 
     
     
       3. The method of  claim 2 ,
 wherein the first hailing rate is asynchronous with respect to the second listening rate, and 
 wherein the second hailing rate is asynchronous with respect to the first listening rate. 
 
     
     
       4. The method of  claim 2 , wherein the second hailing rate is five (5) times the first hailing rate. 
     
     
       5. The method of  claim 4 , wherein the second hailing rate is five (5) hail messages per second, and the first hailing rate is one (1) hail message per second. 
     
     
       6. The method of  claim 2 , wherein the first listening rate is 25% of the second listening rate. 
     
     
       7. The method of  claim 6 , wherein three (3) seconds separate each consecutive instance of listening by the first device, and wherein 750 milliseconds separate each consecutive instance of listening by the second device, wherein the second device is a DC repeater. 
     
     
       8. The method of  claim 2 , wherein the first length of time is about 1.5 times as long as the second length of time. 
     
     
       9. The method of  claim 8 , wherein the first length of time is 276 milliseconds, and the second length of time is 180 milliseconds. 
     
     
       10. The method of  claim 2 , wherein the second hailing rate is five (5) hail messages per second, and the first hailing rate is two (2) hail messages per second. 
     
     
       11. The method of  claim 1 , wherein the predetermined number of symbols is five symbols. 
     
     
       12. A node, comprising:
 a processor; and 
 logic processed by the processor to
 repeatedly transmit, to a network device, a hail message, each transmission of the hail message alternating between two channels, 
 wherein the hail message includes a preamble portion and a data portion separated from one another by a frame, the preamble portion comprising a sequence of symbols and defining a valid channel activity detection (CAD) window extending from a start of the hail message up to a predetermined number of symbols preceding the frame, the preamble portion further defining an invalid CAD window extending for the predetermined number of symbols preceding the frame, and 
 following a failure, during at least one of a first transmission of the hail message and a second transmission of the hail message, to temporally align an instance of listening by the network device with the valid CAD window of the preamble portion, temporally align the valid CAD window of the preamble portion with another instance of listening by the network device, the temporal aligning of the valid CAD window with the another instance of listening by the network device avoiding the invalid CAD window of the preamble portion, and the temporal aligning occurring by no later than an event selected from one of a third transmission of the hail message, the third transmission occurring on one of the two channels, and a sixth transmission of the hail message, the sixth transmission occurring on another one of the two channels. 
 
 
     
     
       13. The node of  claim 12 , wherein the hail message repeatedly transmitted by the node is a first hail message and wherein the logic is further processed by the processor to
 repeatedly transmit the first hail message from the node at a first hailing rate, each transmission of the first hail message comprising a first hail repetition, wherein a first time between beginnings of each first hail repetition is a first period, each first hail repetition is transmitted for a first length of time, and a first gap extends between an end of each first hail repetition and a start of an ensuing first hail repetition, and 
 listen for a second hail message being repeatedly transmitted to the node at a second hailing rate, each transmission of the second hail message comprising a second hail repetition, wherein a second time between beginnings of each second hail repetition is a second period, each second hail repetition is transmitted for a second length of time, and a second gap extends between an end of each second hail repetition and a start of an ensuing second hail repetition, 
 wherein the first period is greater than the second period, the first length of time is greater than the second length of time, and the first gap is greater than the second gap, 
 wherein the logic is further processed by the processor to listen for the second hail message at a first listening rate that is less than a second listening rate of the network device. 
 
     
     
       14. The node of  claim 13 , wherein the logic is further processed by the processor to listen at the first listening rate of 25% of the second listening rate. 
     
     
       15. The node of  claim 14 , wherein three (3) seconds separate each consecutive instance of listening by the node. 
     
     
       16. The node of  claim 13 , wherein the logic is further processed by the processor to set the first length of time at about 1.5 times the second length of time. 
     
     
       17. The node of  claim 13 , wherein the first length of time is 276 milliseconds. 
     
     
       18. The node of  claim 13 , wherein the logic is further processed by the processor to set the first hailing rate to one-fifth of the second hailing rate. 
     
     
       19. The node of  claim 18 , wherein the first hailing rate is one (1) hail message per second. 
     
     
       20. The node of  claim 12 , wherein the predetermined number of symbols is five symbols.